Re-strengthen the check for NBSS continuations, to avoid, for example,

session messages with a zero byte count.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@3971 f5534014-38df-0310-8fa8-9805f1628bb7

diff --git a/packet-nbns.c b/packet-nbns.c
index 5b868ac2d7ed9e4ade1c044780a59f1586082cf5..986faf070519b61f99a30d37bda425529d2e8d1f 100644 (file)
--- a/packet-nbns.c
+++ b/packet-nbns.c
@@ -4,7 +4,7 @@
  * Gilbert Ramirez <gram@xiexie.org>
  * Much stuff added by Guy Harris <guy@alum.mit.edu>
  *
- * $Id: packet-nbns.c,v 1.57 2001/09/28 22:43:56 guy Exp $
+ * $Id: packet-nbns.c,v 1.58 2001/09/29 00:00:26 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -1504,6 +1504,7 @@ dissect_nbss(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
        int             max_data;
        int             len;
        gboolean        is_cifs;
+       static const char zeroes[4] = { 0x00, 0x00, 0x00, 0x00 };
 
        if (check_col(pinfo->fd, COL_PROTOCOL))
                col_set_str(pinfo->fd, COL_PROTOCOL, "NBSS");
@@ -1536,15 +1537,20 @@ dissect_nbss(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 
 #define RJSHACK 1
 #ifdef RJSHACK
-       if ((msg_type != SESSION_REQUEST) && 
+       if (max_data < 4 ||
+           ((msg_type != SESSION_REQUEST) && 
             (msg_type != POSITIVE_SESSION_RESPONSE) &&
             (msg_type != NEGATIVE_SESSION_RESPONSE) &&
             (msg_type != RETARGET_SESSION_RESPONSE) &&
             (msg_type != SESSION_KEEP_ALIVE) &&
-            (msg_type != SESSION_MESSAGE)) {
+            (msg_type != SESSION_MESSAGE)) ||
+           ((msg_type == SESSION_MESSAGE) &&
+            (tvb_memeql(tvb, offset, zeroes, 4) == 0))) {
  
          /*
-          * The first byte isn't one of the known message types.
+          * We don't have the first 4 bytes of an NBNS header, or
+          * the first byte isn't one of the known message types,
+          * or it looks like a session message with a zero header.
           * Assume it's a continuation message.
           */
          if (check_col(pinfo->fd, COL_INFO)) {